Yes I finally found this topic again! First off, miste76 and I share the best day to have a birthday! Go us!!
And yes, the actual day that
Disneyland opened was July 17, 1951 I believe. They probably didn't want the celebration to start right in the middle of summer because of the oppressive heat and it's also one of the busiest times of the year because of school summer vacations. Heat + Lots and lots of regular people = Not a good idea.
Why May 5th though? I have no idea.